Refactor according to Jon's suggestion

sceptre/cli/helpers.py

@@ -1,5 +1,7 @@
 import logging
+import os
 import sys
+import traceback
 
 from itertools import cycle
 from functools import partial, wraps
@@ -32,14 +34,15 @@ def catch_exceptions(func):
     def decorated(*args, **kwargs):
         """
         Invokes ``func``, catches expected errors, prints the error message and
-        re-raises.
+        exits sceptre with a non-zero exit code.
         """
         try:
             return func(*args, **kwargs)
         except (SceptreException, BotoCoreError, ClientError, Boto3Error,
-                TemplateError) as error:
-            write(error)
-            raise
+                TemplateError):
+            if "DEBUG_ERRORS" in os.environ:
+                traceback.print_exc()
+            sys.exit(1)
 
     return decorated
 

tests/test_cli.py

@@ -55,13 +55,14 @@ def teardown_method(self, test_method):
         self.patcher_ConfigReader.stop()
         self.patcher_StackActions.stop()
 
-    def test_catch_excecptions(self):
+    @patch("sys.exit")
+    def test_catch_excecptions(self, mock_exit):
         @catch_exceptions
         def raises_exception():
             raise SceptreException()
 
-        with pytest.raises(SceptreException):
-            raises_exception()
+        raises_exception()
+        mock_exit.assert_called_once_with(1)
 
     @pytest.mark.parametrize("command,files,output", [
         # one --var option